that rGE in the family context as an important pathway of risk to alcohol use outcomes. For example, Elam et al. (2018) showed that polygenic risk for aggression was associated with lower levels of family cohesion in adolescence, which in turn was associated with alcohol use in young adulthood. We did not find significant associations between alc-GPS and friend support. This is inconsistent with previous research that provided evidence of rGE in the peer/friend context. For example, polygenic risk for behavioral disinhibition was associated with affiliation with substance-using peers, in part via higher impulsivity and lower parental monitoring (Elam et al., 2017). It is possible that genetic predispositions toward alcohol use influence individuals’ choice and selection of friends who share predispositions and behaviors similar to themselves, but do not influence the perception of amount and quality of support they receive from friends. Future research is needed to replicate our findings and also consider the role of other peer contextual factors such as peer substance use in linking genetic predispositions to alcohol use outcomes.
